US Election 2012: Idiots Guide To Election Night, What States To Watch And When

On Tuesday Americans will choose their next president. But how does the process actually work?

The last polls of the campaign showed Barack Obama and Mitt Romney roughly tied nationally in the polls.

However it is not the overall national share of the vote that matters, rather how many votes in the electoral college each candidate gets.

Each state has a different number of votes depending on its population. California, with a population of over 37 million, has 55. But Rhode Island which has a population of just one million gets only four.

The magic number is 270. Which ever candidate manages to secure 270 votes in the electoral college captures the White House.

In 2008 Obama won in a electoral college landslide with 358 to John McCain's 180. But in 2004 it was much closer, when George Bush won a second term with 285 to John Kerry's 253.

The electoral college system makes it possible for one candidate to win a majority of the national vote, but lose the election.

In 2000 Al Gore polled half a million more votes nationwide than George W. Bush. But after the controversial recount in Florida, Bush won the White House by - eventually - being awarded Florida's 29 electoral college votes.

Swing States

Just as British political parties have 'safe seats', the Republicans and Democrats have states that they can rely on to vote their way. Texas (38 electoral votes) has voted Republican since 1980, while New York (29 electoral votes) has voted Democratic since 1988.

The election will come down to a handful of "swing states" including Ohio, Florida, Colorado and New Hampshire.

According to polling firm YouGov Obama will win win 18 states (including Washington DC) comfortably - giving the president an absolute minimum of 237 Electoral College votes; 33 short of his target.

Writing on The Huffington Post UK, YouGov's president Peter Kellner says Mitt Romney holds clear leads in 24 states - giving him 191 electoral college votes, 79 short of victory.

Kellner says: "That leaves nine states up for grabs. They provide 110 electoral votes. Obama needs to win just under a third of them; Romney needs almost three-quarters of them."

State

Sample size (likely voters)

Electoral College votes

Lead (%)

Obama ahead

New Hampshire

690

4

4

Nevada

732

6

4

Wisconsin

1225

10

4

Ohio

1620

18

3

Virginia

1497

13

2

Iowa

1040

6

1

Colorado

752

9

1

Romney ahead

Florida

1621

29

1

North Carolina

1500

15

2

What Times Should You Be Watching?

The United States also has multiple timezones, meaning polls close across the country at different times. NBC news has produced a handy list of when each state's poll close and TV networks will make projections.

All times are in Eastern Standard Time (EST) which is five hours behind GMT meaning watching the election live in the UK is going to require a few cans of energy drink or cups of coffee.